High efficiency cyclotron-wave parametric amplifier and harmonic generator



Aprll 19, 1966 WADE HIGH EFFICIENCY CYCLOTRON-WAVE PARAMETRIC AMPLIFIER AND HARMONIC GENERATOR Filed April 14, 1964 G Zen 1W2; 34 m:

Agg-

United States Patent 3,247,395 HEGH EFFICRENCY CYCLOTRON-WAVE PARA- METRIC AMPLIFIER AND HARMONHC GENER- TOR Glen Wade, Wayland, Mass, assignor to Zenith Radio Corporation, Chicago, Ill., a corporation of Delaware Filed Apr. 14, 1964, Ser. No. 35%754 12 Claims. (Cl. 30788.3)

This invention relates to electron beam devices. More particularly, it pertains to parametrically-pumped cyclotron-mode electron beam devices having applications as amplifiers, oscillators, and frequency multipliers, or the like.

The basic electron beam parametric pumping mechanism is now Well known and has been the subject of extensive discussion in the literature. The technique has found particular utility in cyclotron-mode, or the socalled O-type, devices. Briefly, in such devices an input signal is modulated on an electron beam projected through a magnetic field which establishes a condition of cyclotron resonance. In response to the input signal energy, the electrons are caused to follow helical orbits along the beam path with an orbital period corresponding to the strength of the magnetic field. The electron motion is then caused to expand in radius, representing an increase in signal energy, by subjecting the electrons to a periodic inhomogeneous pumping field having a pattern and periodicity to cause forces to be exerted on the electrons. Subsequently, the amplified signal energy is extracted from the electron beam.

A particularly suitable parametric pumping mechanism is described and claimed in my copending application Serial No. 289,792 filed June 20, 1963, which in turn is a continuation of my earlier application Serial No. 747,764 filed July 10, 1958, and now abandoned, all of these applications being assigned to the same assignee. As fully explained in those applications, the orbiting electrons preferably are subjected to a periodic quadrupoleshaped field having a periodicity such that the moving electrons in the electron beam are subjected to four reversals of the field for each period of the orbital electron motion. The technique involved and suitable structure therefor also are described in an article entitled A Low-Noise Electron-Beam Parametric Amplifier which appeared on pages 1756-1757 of the October 1958 issue of the Proceedings of the I.R.E.

In the simplest consideration of the parametric pumping mechanism, the pumping field variation is considered as being at a frequency twice that of the input signal frequency. However, as further explained in the aforesaid applications, the actual frequency of the source of energization for the pumping structure may be considerably different from that value. As one example there explained, the field may be skewed in a direction around the beam path in which case the pump supply frequency is lowered an amount proportional to the degree of skew. This approach leads to a combined influence upon the orbiting electrodes, one which is due to a time-alternation of the field and another which is due to the spatial periodicity of the field in a direction parallel to the beam path. And as claimed and described in my copending application 840,336 filed September 16, 1959,

entitled, Modulation Expander for Parametric Amplifiers, and also assigned to the same assignee, the entire variation of the pumping field may be one of spatial periodicity. In the illustrative embodiment of the latter application, a quadrupole pumping structure is twisted to have a pitch the same as that of the orbital paths followed by the moving electrons. In this case, the pump ing frequency is zero, or, in other Words, the pump structure isenergized from a unidirectional source to create a static field.

The capability of utilizing a unidirectional-potential pump source is attractive for many apph'cations. One such application is the power amplifier where it is desired to achieve a high order of power gain at comparatively high frequencies, while yet utilizing a minimum amount of attendant equipment. However, one of the limitations often encountered in various types of power amplifiers lies in the efliciency of the devices. Where high power levels are involved, it is important that the dissipation of energy be minimized. In the DC pumped parametric amplifier mentioned above, not all of the electrons initially modulated with input signal energy are acted on by the pumping field in a manner which renders them capable of readily yielding all of their energy to the output or load coupler. To the extent that energy remains in the modulated electrons following the signal output extraction stage, the efficiency is reduced because such remaining energy must subsequently be dissipated in the beam collector. 1

It accordingly is a general object of the present invention to provide an electron beam device in which the operational etficiency is increased.

It is a more specific object of the present invention to provide an electron beam power amplifier capable of producing high gains but yet minimizing power dissipation.

A related object of the present invention is to provide an electron beam device of the aforesaid character which requires simple, easily-designed and fabricated individual stages and which minimizes the complexity of associated equipment.

Related to the foregoing is the recognition that the cyclotron-mode pumping process involves the develop ment of electron signal motion not only in the transverse direction but also in the longitudinal direction of the beam path. Generally speaking, and particularly with respect to efficiency of operation as referred to above, the longitudinal-mode energy components are undesired, and it is a particular aim of the present invention in accordance with one aspect thereof to minimize the existence of such longitudinal-mode components. On the other hand, a related aspect of the present invention pertains to utilization of the aforesaid longitudinal-mode components.

It is therefore a further object of the present invention to provide an electron beam device of the cyclotronmode type but in which advantage is taken of longitudinal-mode electron-motion components.

A still further and related object of the present invention is to provide an electron beam device which may be of a generally conventional cyclotron-mode type but which serves as a signal frequency harmonic multiplier.

In its one aspect, the invention is embodied in an electron beam device in which the beam is projected along a predetermined path and is subjected to a field which establishes acondition of cyclotron resonance. The beam is density modulated along a first path portion while at the same time it is transversely modulated along a second path portion with both the modulations being related to the input signal frequency. Along a third path portion, the modulated electrons are subjected to an inhomogeneous periodically varying field which parametrically amplifies the energy level of the transverse modulation. Finally, the device includes means for extracting amplified signal energy from the electron beam.

Followingthe principles disclosed hereinafter, another aspect of the present invention involves an embodiment featuring 'a cyclotron-mode electron beam device which includes means disposed along" a first path portion for transversely modulating the beam in response to input signal modulation together with a pumping means for subjecting the modulated electrons to aperiodic inhomogeneous field in order t6 parametrically amplify thetransverse' electron signal motion. As a result of, the pumping mechanism, ohe periodic 'siic'cession of electron groups are accelerated in the direction ofthe beam path and another such succession of groups interleaved with the first are decelerated in that direction. Disposed downstream of the pumping mechanism is a structure responsive to density modulation on theelectron beam for extracting signal energy therefrom. The extracted signal energy is harmonically related to the input signal energy and may be utilized either by feeding it to an external load device or for density modulating the beam in the device according to the first-mentioned aspect of the invention.

The features of the present invention which are believed to be novel are set forthwith particularity in the appended claims. The organization and manner of operation of the invention, together with further objects and advantages thereof may best be understood by reference to the accompanying description taken in connection with the accompanying drawings, in the several figures of which like numerals identify like elements, and in which:

FIGURE 1 is a diagrammatic perspective view illustrating one embodiment of the present invention;

FIGURE 2 is a diagrammatic perspective view of another embodiment of the present invention; and

FIGURES 3 and 4 are motion diagrams helpful in explaining the operation of the embodiments illustrated in FIGURES l and 2. V k

As shown inFIGURE 1 for the purpose of illustrating the present invention, an electron. beam device includes a cathode which is part ofa conventional Pierce-type electron gun 11 also including focusing electrode 12 and an apertured beam forming electrode 13. Electron gun 11 projects an electron beam along a path 14 toward a collector 15. The entire path is immersed in a magnetic field, indicated by arrow H, having its flux lines parallel to the path. The magnetic field establishes for the electrons in the beam a condition of cyclotron'resonance, the resonant frequency being a function of the strength of the field.

Disposed along the beam path are an input signal coupler 16, a pump 17 and an output coupler 18. In response to input signal energy from a source 19, coupler 16 interacts with the electron beam to cause the electrons to follow orbits which define helical paths coaxial with the beam path. The radius of the orbital paths is proportionalto and therefore representative of the input signal strength. The periodicity of the paths corresponds to the cyclotron frequency. The electron pattern developed defines a fast electron wave.

Pump 17 is a quadrifilar helix 20 with its successive turns being alternately polarized positive and negative by a unidirectional pump source 21. The pitch of the individual windings of helix 20 is the same as that of the helical paths traversed by the moving electrons. Consequently, the electrons are subjected to an inhomogeneous periodically varying field which has an intensity proportional to distance away from the beam path and a periodic variation with a phase related to that of the transverse signal modulation such that forces on the electrons increase the energy level of the transverse modulation.

More particularly, the field of pump 17 has a quadrupole shape which is skewed around the beam path in a direction therealong. It is unidirectional in the timedomain and defines a field pattern with a plurality of pairs of space-opposed poles disposed along interleaved helicoidal loci which are coaxial with the helical electron motion paths. In addition to being of the same pitch as the paths, the helicoidal loci are co-directional therewith and have a coaxial length corresponding to at least one convolution of the paths. The even-numbered pairs of the field poles are of one polarity and odd-numbered pairs of the poles are of the opposite polarity.

The augmented or expanded energy appears as an increased radius of the electron motion. The totality of the individual electron motion defines an electron wave with which coupler 18 interacts and extracts amplified signal energy which is fed to a load 22.

As'thus-far discussed, the device shown in FIGURE 1 is describe-d and claimed in my aforesaid application 840,- 336. A further analysis of the operational characteristics will facilitate understanding of the present invention. The helically moving electrons leaving input coupler 16 may be considered as intersecting an imaginary plane 24 across the entrance of pump 17 to sweep out a circular path 25 as depicted in FIGURE 3. Electrons intersecting plane 24 at points A and C follow helical paths connecting respective points of maximum tangential acceleration located generally 45 behind positions under a positively polarized pair of the windings of quadri-filar helix 17, while electrons intersecting plane 24 at points B and D follow paths connecting respective points of maximum tangential deceleration located generally, 45 behind positions under the other helix pair which is polarized negatively. Consequently, the electrons following one set of paths are attracted outwardly while the electrons following the other set of paths are repelled inwardly. The radius of electronmotionof electrons on paths A and C is increased while that on paths B and D is decreased.

Because of the unequal effects on different parts of the beam, its pattern is oval shaped upon leaving the pump region. FIGURE 4 depicts the curve traced'out-by the electrons intersecting a transverse plane 27 across the exit of the pump structure. The excitation of output coupler 1-8 is primarily influenced by the electrons thrown out the farthest from the beam path, which in this case would be those electrons following p'athsA and C. Coupler 18 may have a length sufiicient to extract all energy from these outermost electrons. However, the electrons on paths B and D emerge from the output coupler with additional energy absorbed therefrom, since the interaction process in the coupler involves. a two-Way flow of energy. Stated another way, while coupler 18 absorbs or extracts energy from electrons following paths A and C, it at the same time modulates or imparts energy to the electrons. following paths B and D. This energy retained by the beam is dissipated in collector 15 and represents wasted power.

In accordance with the invention, the groups of electrons which would be so phased upon entrance to the pumping region as to be decelerated are shifted in longitudinal position relative to the beam path so as to assume a position in which they are subjected to an accelerating influence. To this end, a velocity-modulation or longitudinal-mode electron coupler 28 is disposed along the initial portion of the beam path and fed by energy derived from input signal's'ource 19. Coupler 28 modulates the electron beam in the same manner as the input coupler described in Patent 3,090,025 issued May 21, 1963, to Robert Adler and Glen Wade and assigned to the same assignee as the present application. As in the case of that coupler, coupler 28 may be of any conventional type for velocity modulating an electron beam. As illustrated it is a conventional helix, but it could also take such forms as a pair of spaced gaps or a cavity.

In operation, coupler 28 modulates the beam with the signal energy so that the electrons are caused to arrive at input coupler 16 and pump 17 in bunches. The spacing between couplers 16 and 28 and the beam velocity are selected so that the electron bunches of the helically orbiting electrons, upon subsequent intersection with plane 24, are concentrated at points A and C in FIGURE 3. In consequence of the bunching process, the electrons that would have arrived at plane 24 at points B and D in FIG- URE 3 are moved away from those points toward points A and 'C so that the number of electrons entering the quadrupole region in the correctly phased maximum-gain position is increased. Similarly, the number of electrons arriving at points B and D in exit plane 27 is decreased. The pattern of the exciting beam remains the same but the density of electrons along the beam varies in a way such that the total number of electrons capable of interacting with output coupler 18 to undesirably absorb energy from that coupler is minimized.

It will be noted that, during one signal cycle as seen by the electrons, the electrons individually travel once around the entire path illustrated in FIGURE 3; an electron during that travel courses through two good points and two bad points for amplification efficiency. Consequently, it is desired that there be two density modulation bunches per cycle. To this end, coupler 28 is driven either with the second harmonic of the input-signal frequency from source 19, or, if the fundamental signal frequency is fed to coupler 28, the bunching is caused to be so tight that a significant second harmonic exists due to non-linearities in the beam with the second harmonic corresponding to a maximum amplitude at point A or at point C as depicted in FIGURE 3. When coupler 28 is driven with the second harmonic, the latter may be derived either from source 19 or a frequency double may be inserted between source 19 and coupler 2 8. In any case, the signal frequency of interest with respect to the velocity modulation is harmonically related to the frequency of the input signal applied to coupler 16; the harmonic relationship usable therefore may include the first harmonic.

In principle, the bunching or density alignment of the electrons may take place anywhere upstream from the pumping region, and the transverse-modulation and velocity-modulation coupler structures may be disposed in either order or combined. However, it is preferred to place the velocity-modulation coupler first to allow sufficient drift space for the bunches to develop fully.

' As discussed above, the action of pump 17 is to treat differently phased electrons in an opposing manner. In addition to the forces exerted by pump 17 upon the moving electrons in a transverse direction, they are also subjected by the pump to forces in the longitudinal direction. The spatial periodicity of the twisted quadrupole pump structure in a direction along the beam path causes a velocity-modulation of the electron beam as it traverses the pumping region. One periodic succession of electron groups is accelerated in the direction of the beam path while another succession of such groups interleaved with the first group is decelerated. Since the periodic variation of the pumping field appears to the electrons as occurring at a rate twice that of the cyclotron frequency, which is twice the effective input signal frequency, the periodic variation of the static pumping field in a direction along the path is at a rate which is also twice the input signal frequency. Consequently, the density modulation imposed upon the beam by pump 17 is at a frequency twice the input frequency. At the same time, the transverse forces exerted by pump 17 inherently causes a phase focusing of the electrons tending to optimize proper spatial alignment of the electrons with the electrodes for maximum gain; this augments the action of coupler 28. The form of the invention illustr'ated'in FIGURE 2 6 closely resembles that of FIGURE 1 except that input coupler 28 is omitted and output coupler 18 is replaced by a longitudinal-mode electron coupler 30. The other elements in FIGURE 2 operate in the same manner as those in FIGURE 1. Velocity-modulation coupler. 30 interacts with the longitudinal-mode beam components of the beam after it leaves pump 17 and extracts signal energy from the beam for delivery to load 22. Because of the longitudinal-mode action in pump 17 as explained above, coupler 30 responds to the density modulation on the beam by interacting at a frequency twice the input signal frequency. Consequently, the device of FIGURE 2 is a frequency doubler. It is particularly attractive as a source of high frequency signals While requiring as associated'equipment an input signal source of a barmonically' related lower signal frequency. Further, frequency doubling is accomplished Without the need fora second finiteifrequency source, pump 17 requiring only a unidirectional potential source.

The features of operation realized from the device of FIGURE 2 may be combined directly into the device of FIGURE 1 by the simple expedient of positioning velocity-modulation coupler 30 in the output portion of the device of FIGURE 1, as between pump 17 and coupler 18, and coupling energy derived by coupler 30 to velocitymodulation input coupler 28. That is, coupler 28 is fed with energy from coupler 30 instead of from source 19. As explained above, it is desired that there be two density modulation bunches per cycle as the beam in the FIGURE 1 device enters pump 17 and that for this purpose coupler 28 may be driven with a second harmonic of the input signal frequency. As also explained above with reference to FIGURE 2, coupler 30 responds to the densitymodulation on the beam by interacting at a frequency twice the input signal frequency. In the combined device the energy fed from coupler 30 to coupler 28 is inherently at the correct frequency for operation in accordance with the overall principles explained with respect to FIGURE 1.

In operation of the combined device, a signal fed to input coupler 16 modulates the beam in the transverse mode and this modulation is amplified by pump 17. The latter also effects modulation of the beam in the longitudinal mode at the second harmonic of the input signal. Output coupler 18 extracts the amplified input signal energy, while longitudinal-mode coupler 30, in the output portion of the beam path, extracts the second harmonic signal which, in turn, is applied to longitudinal-mode coupler 23 in order to density modulate the beam and thereby bring about the density alignment desired for maximum performance. Any tendency for regeneration in the loop completed by intercoupling the two longitudinal-mode couplers is avoided either by including an attenuator between the two or simply by constructing one or the other to have but weak coupling efficiency.

. The apparatus described above in all embodiments of the present invention is characterized as being of the cyclotron-mode or O-type class of electron beam apparatus. However, the inventive principles involved pertain to longitudinal-mode interaction. The new combinations made possible in accordance with the principles of the invention take advantage of longitudinal-mode effects present in that which is basically a cyclotron-mode device. As a result of this different approach, the efficiency of operation in what otherwise is a known device may be substantially improved; this is an attribute particularly desirable in power amplifiers. In the second discussed form of the invention, a frequency multiplier requires but one input source of finite frequency signals, since there is no heterodyning of signals of two finite frequencies. The apparatus is capable of developing extremely high frequency signal energy while utilizing parametic electron beam apparatus otherwise having the design features attendant to much lower frequency operation. Finally, the features of the two illustrated devices may be directly combined so that the longitudinah mode output coupler of FIGURE 2 when placed in the device of FIGURE 1 supplies the desired longitudinalmode excitation for the latter device. I

While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and, therefore, the aim in the appended claims is means for subjecting the electrons in said' beam to a field establishing a: condition of cyclotron resonance;

means disposed alonga first path portion for density modulating said beam at a frequency harmonicallyrelated to an input signal frequency;

"means disposed along a second path portion: for transversely modulating said beam atsaid input signal frequency;

means disposedalong a third path portion downstream of said first and second portions for subjecting said electrons to an inhomogeneous periodically varying field the intensity of which varies in proportion to distance away from said path and the periodic variation of which has a phase relationship with a; transverse signal modulation on said beam such that forces on said electrons increase theenergy level of said transverse modulation;

and means disposed downstream of said third path portion for extracting amplified signal energy from said beam.

2. Anelectron beam device comprising;

means for projecting an electron beam along a predetermined path;

means for subjecting the electrons in said beam to a fieldestablishing a'condition of cyclotron resonance;

' means disposed along a first path portion for density modulating said beam at a frequency harmonically related to an input signal frequency;

means disposed along a second path portion downstream from said first path portion for transversely modulating said beam at said input signal frequency;

means disposed along a third path portion downstream from' said second portion for subjecting said electrons to an inhomogeneous periodically varying field the intensity of which varies in proportion to distance away from said path and the periodic variation of which has a phase relationship withthe transverse signal modulation on said beam such that forces on said electrons increase the energy level of said transverse modulation; 7

and means disposed downstream of said third path portion for extracting amplified signal energy from said beam.

3. An electron beam device comprising:

means for projecting an electron beam along a predetermined path;

means for subjecting the electrons in said beam to a field establishing a condition of cyclotron resonance;

means disposed along a first path portion for density modulating said beam at a frequency harmonically related to an input signal frequency;

means disposed along a second path portion for transversely modulating said beam at said input signal frequency;

means disposed along a third path portion downstream of said-first and second portions for subjecting said electrons to an inhomogeneous periodically varying field the intensity of which varies in proportion todistance away from said path and the periodic variation of which has a phase relationship with the transverse signal modulation on said beam such that forces on said electrons increase the energy level of said transverse modulation, the cross-section of said field being skewed around said path in a direction therealong;

and means disposed downstream of said third path portion for extracting amplified signal energy from said beam.

4. An electron beam device comprising:

means for projecting an electron beam along a predetermined path;

means for subjecting the electrons in said beam to a field establishing a condition of cyclotron resonance;

means disposed along 'a first path portion for density modulating said beam at afrequency harmonically related to an input signal frequency;

means disposed along a second path portion for transversely modulating. said' beam at said input signal frequency;

means disposed along a: third path portion downstream of said first and second portions for subjecting said electrons to non-homogeneous field forces, the strength of which varies in proportion to distance away from said path, unidirectional in a time-domain, and defining a field pattern with a plurality of pairs of space-opposed poles disposed along interleaved helicoidal loci which are coaxial with helical paths coursed by the electrons in response to said transverse signal modulation and said condition of cyclotron resonance, said helicoidal loci being of the same pitch as and co-directional with said helical paths and having a coaxial length corresponding to at least one convolution of said helical paths, the even numbered pairs of said poles being of one polarity and the odd numbered pairs of said poles being of the opposite polarity;

and means disposed downstream of said third path portion for extracting amplified signal energy from said beam.

5. An electron beam device comprising:

means for projecting an electron beam along a predetermined path;

means for subjecting the electrons in said path to a field establishing a condition of cyclotron resonance;

means disposed along a first pat-h portion for density modulating said beam at a frequency harmonically related to an input signal frequency;

means disposed along a second path portion for transversely modulating said beam at said input frequency and creating fast electron waves on said beam representative of said input signal frequency;

means disposed along a third path portion downstream from said first and second portions for subjecting said electrons to an inhomogeneous periodically varying field the intensity of which varies in proportion to distance away from said path and the periodic variation of which has a phase relationship with the transverse signal variation on said beam such that forces on said electrons increase the energy level of said transverse modulation;

and means disposed downstream of said third path portion for extracting amplified signal energy from said beam.

6. An electron beam device comprising:

means for projecting an electron beam alonga predetermined path;

means for subjecting the electrons in said beam to a field establishing a condition of cyclotron resonance;

means disposed along a first path portion for density modulating said beam at a predetermined frequency;

means disposed along a second path portion for transversely modulating said beam at an input signal frequency harmonically related to said predetermined frequency;

means disposed along a third path portion downstream of said first and second path portions for subjecting 9 said electrons to an inhomogeneous periodically varying field the intensity of which varies in proportion to distance away from said path and the periodic variation of which has a phase relationship with the transverse signal modulation on said beam such that forces on said electrons increase the energy level of said transverse modulation; and means disposed downstream of said third path portion for extracting amplified signal energy from said beam. 7. In a cyclotron-mode electron beam device in which an electron beam is projected along a predetermined path and transversely modulated with input signal energy to develop cyclotron-mode waves representative of the signal;

means for subjecting said electrons to an inhomogeneous periodically varying field the intensity of which varies in proportion to distance away from said path and the periodic variation of which has a phase relationship with the transverse signal modulation on said beam such that forces on said electrons increase the energy level of said transverse modulation, a periodic succession of electron groups being accelerated in the direction of said path;

and a longitudinal field electron coupler disposed along said path for interacting in the velocity mode with signal energy on said beam at a frequency harmonically related to the input signal frequency.

8. An electron beam device comprising:

means for projecting an electron beam along a predetermined path;

means for subjecting the electrons in said beam to a field establishing a condition of cyclotron resonance;

means disposed along a first path portion for transversely modulating said beam at an input signal frequency;

means disposed along a second path portion downstream of said first portion for subjecting said electrons to an inhomogeneous periodically varying field the intensity of which varies in proportion to distance away from said path and the periodic variation of which has a phase relationship with the transverse signal modulation on said beam such that forces on said electrons increase the energy level of said transverse modulation, one periodic succession of electron groups being accelerated in the direction of said path and another succession of such groups interleaved with the first group being decelerated in said direction;

and mean-s, disposed downstream of said second portion, responsive to density modulation on said beam for extracting signal energy therefrom.

9. An electron beam device comprising:

means for projecting an electron beam along a predetermined path;

means for subjecting the electrons in said beam to a field establishing a condition of cyclotron resonance;

means disposed along a first path portion for transversely modulating said beam at an input signal frequency;

means disposed along a second path portion downstream of said first portion for subjecting said electrons to an inhomogeneous periodically varying field the intensity of which varies in proportion to distance away from said path and the periodic variation of which has a phase relationship with the transverse signal modulation on said beam such that forces on said electrons increase the energy level of said transverse modulation, one periodic succession of electron groups being accelerated in the direction of said path and another succession of such groups interleaved with the first group being decelerated in said direction with such alternate acceleration and deceleration being periodic at a frequency twice said input signal frequency;

and means, disposed downstream of said second portion, responsive to density modulation on said beam for extracting signal energy therefrom at a frequency twice said input signal frequency.

10. An electron beam device comprising:

means for projecting an electron beam along a predetermined path;

means for subjecting the electrons in said beam to a field establishing a condition of cyclotron resonance;

means disposed along a first path portion for transversely modulating said beam at an input signal frequency;

means disposed along a second path portion downstream of said first portion for subjecting said electrons to an inhomogeneous periodically-varying field the intensity of which varies in proportion to distance away from said path and the periodic variation of which has a phase relationship with the transverse signal modulation on said beam such that forces on said electrons increase the energy level of said transverse modulation with the cross-section of said field being skewed around said path in a direction therealong, one periodic succession of electron groups being accelerated in the direction of said path and another succession of such groups interleaved with the first group being decelerated in said direction;

and means, disposed downstream of said second portion, responsive to density modulation on said beam for extracting signal energy therefrom.

11. An electron beam device comprising:

I means for projecting an electron beam along a predetermined path;

means for subjecting the electrons in said beam to a field establishing a condition of cyclotron resonance;

means disposed along a first path portion for transversely modulating said beam at an input signal frequency;

means disposed along a second path portion downstream from said first portion for subjecting said electrons to non-homogeneous field forces, the strength of which varies in proportion to distance away from said path, unidirectional in a timedomain, and defining a field pattern with a plurality of space-opposed poles disposed along interleaved helicoidal loci which are coaxial of the helical paths coursed by said electrons in response to said transverse modulation and said condition of cyclotron resonance, said helicoidal loci being of the same pitch as and co-directional with said helical paths and having a coaxial length corresponding to at least one convolution of said helical paths with the even numbered pairs of said poles being of one polarity and the odd numbered pairs of said poles being of the opposite polarity, one periodic succession of electron groups being accelerated in the direction of said path and another such succession of groups interleaved with said first group being decelerated in said direction;

and means, disposed downstream of said second portion, responsive to density modulation on said beam for extracting signal energy therefrom.

12. An electron beam device comprising:

means for projecting an electron beam along a predetermined path;

means for subjecting the electrons in said beam to a field establishing a condition of cyclotron resonance;

means disposed along a first path portion for density modulating said beam at a frequency harmonically related to an input signal frequency;

means disposed along a second path portion for transversely modulating said beam at said input signal frequency;

means disposed along a third path portion downstream of said first and second portions for subjecting said electrons to an inhomogeneous periodically varying field the intensity of which varies in proportion to distance away from said path and the periodic variation of which has a phase relationship with the transverse signal modulation on said beam such that forces on said electrons increase the energy level of said transverse modulation, with one periodic succession of electron groups being accelerated in the direction of said path and another succession of such groups interleaved with the first group being decelerated in said direction;

means, disposed downstream of said third portion, re-

sponsive to density modulation on said beam for extracting signal energytherefrom and supplying the same to said density-modulation means; H and additional means disposed downstream of said third path portion for extracting amplified transverse-mode signal energy from said beam.

No references cited.

10 ROY LAKE, Printary Examiner. 

1. AN ELECTRON BEAM DEVICE COMPRISING: MEANS FOR PROJECTING AN ELECTRON BEAM ALONG A PREDETERMINED PATH; MEANS FOR SUBJECTING THE ELECTRONS IN SAID BEAM TO A FIELD ESTABLISHING A CONDITION OF CYCLOTRON RESONANCE; MEANS DISPOSED ALONG A FIRST PATH PORTION FOR DENSITY MODULATING SAID BEAM AT A FREQUENCY HARMONICALLY RELATED TO AN INPUT SIGNAL FREQUENCY; MEANS DISPOSED ALONG A SECOND PATH PORTION FOR TRANSVERSELY MODULATING SAID BEAM AT SAID INPUT SIGNAL FREQUENCY; MEANS DISPOSED ALONG A THIRD PATH PORTION DOWNSTREAM OF SAID FIRST AND SECOND PORTIONS FOR SUBJECTING SAID ELECTRONS TO AN INHOMOGENEOUS PERIODICALLY VARYING FIELD THE INTENSITY OF WHICH VARIES IN PROPORTION TO DISTANCE AWAY FROM SAID PATH AND THE PERIODIC VARIATION OF WHICH HAS A PHASE RELATIONSHIP WITH A TRANSVERSE SIGNAL MODULATION ON SAID BEAM SUCH THAT FORCES ON SAID ELECTRONS INCREASE THE ENERGY LEVEL OF SAID TRANSVERSE MODULATION; AND MEANS DISPOSED DOWNSTREAM OF SAID THIRD PATH PORTION FOR EXTRACTING AMPLIFIED SIGNAL ENERGY FROM SAID BEAM.
 7. IN A CYCLOTRON-MODE ELECTRON BEAM DEVICE IN WHICH AN ELECTRON BEAM IS PROJECTED ALONG A PREDETERMINED 